Heat spreading system, electronic equipment, closed fluid heat spreading loop, electronic componenet, and a heat spreading system produced by a production method

Abstract

A heat spreading system (210) for transferring thermal heat from a die (220) in an electronic component to a heat sink (230) is provided. The heat spreading system is characterized by comprising the heat sink (230), and in-between the heat sink (230) and the die (220), a closed fluid heat spreading loop (240). The closed fluid heat spreading loop comprises a fluid channel (260) adapted to contain a fluid and is encapsulated in a body (270). The body (270) is in contact with the die (220) and the heat sink (230) to transfer thermal heat from the die to the heat sink (230).

Description

[0001] HEAT SPREADING SYSTEM, ELECTRONIC EQUIPMENT, CLOSED FLUID HEAT SPREADING LOOP, ELECTRONIC COMPONENET, AND A HEAT SPREADING SYSTEM PRODUCED BY A PRODUCTION METHOD

[0002] TECHNICAL FIELD

[0003] Embodiments herein relate to a heat spreading system, an electronic equipment, a closed fluid heat spreading loop, a microprocessor and a heat spreading system produced by a production method.

[0004] In some aspects, the heat spreading system is for transferring thermal heat from a die of a heat generating component in an electronic equipment, to a heat sink.

[0005] In some further aspects, the microprocessor comprises a heat spreading system, the closed fluid heat spreading loop is adapted to be comprised in the heat spreading system, and the electronic equipment comprises a heat spreading system.

[0006] BACKGROUND

[0007] Thermal design and thermal heat transfer is on the edge of what is possible for the telecom industry. This is due to increased power in telecom products, such as base stations and mobile phones, and decreased size and volume of the telecom products. The traditional thermal chain where heat is dissipated from a component lid to a heat sink has reached its limits and is in need for new solutions. The main drawback with this solution is that each layer of Thermal Interface Material (TIM) adds a penalty in a die temperature.

[0008] US 8,115,303 B2 presents semiconductor package structures, which are designed to have liquid coolers integrally packaged with first level chip modules. In particular, apparatus for integrally packaging a liquid cooler device within a first level chip package structure include structures in which a liquid cooler device is thermally coupled directly to the back side of an integrated circuit chip flip-chip mounted on flexible chip carrier substrate. The liquid cooler device is mechanically coupled to the package substrate through a metallic stiffener structure that is bonded to the flexible package substrate to provide mechanical rigidity to the flexible package substrate.

[0009] SUMMARY As a part of developing embodiments herein a problem was identified by the inventors and will first be discussed.

[0010] In traditional designs, the silicon die is enclosed with a lid, and a heat spreading device is placed between the lid and the heat sink to improve the heat release rate.

[0011] Figure 1 depicts a traditional cooling chain comprising TIM 1 with a lid 10 and a heat spreader 20, also referred to as vapor chamber between a die 30 and a heat sink 40. The die 30, a substrate 50, the lid 10 and TIM 1 make up an electronic component. The heat sink 40 may e.g. be a passive heat exchanger that transfers the heat generated by the die 30 to a fluid medium, often air or a liquid coolant, where it is dissipated away from the electronic component, thereby allowing regulation of the electronics’ temperature. A heat sink is often equipped with fins in order to transmit it to the environment for efficient cooling.

[0012] Designs of today for heat transfer between components such as a Printed Circuit Board (PCB) 60 and the heat sink 40 are based on physical contact under pressure with a TIM layer in between. The purpose of the TIM layer is to transfer heat, fill in the small air gaps between components and heat sink caused by surface roughness and compensate for mechanical tolerances. In Figure 1 three TIM layers are disclosed, TIM 1 which is used for transferring the heat from the die 30 to the lid 10, TIM 2 which is used for transferring heat from the lid 10 to the heat spreader 20, and TIM 3 which is used for transferring heat from the heat spreader 20 to the heat sink 40, plus compensate for manufacturing tolerances. The properties of the TIM layers will change over time due to aging, causing lower performance and leading to reliability problems.

[0013] In a TIM layer, outgassing, also referred to as pump out, causes solvent separation, for example oil, which may interact chemically with electronic components in harmful ways.

[0014] Adding a TIM layer between an electronic component and the heat sink 40 requires manufacturing phases which can be shortened the less TIM a product has. PCB is a board made from a sandwich of fibreglass and copper to provide wiring between components which are soldered onto it. The electronic component is soldered onto the PCB.

[0015] An object of embodiments herein is to provide an improved heat spreading system for transferring thermal heat from a die of a heat generating component in an electronic equipment to a heat sink. According to another aspect of embodiments herein, the object is achieved by a heat spreading system for transferring thermal heat from a die of a heat generating component in an electronic equipment to a heat sink. The heat spreading system is characterized by comprising the heat sink, and in-between the heat sink and the die, a closed fluid heat spreading loop. The closed fluid heat spreading loop comprises a fluid channel adapted to contain a fluid and is encapsulated in a body. The body is in contact with the die and the heat sink to transfer thermal heat from the die to the heat sink.

[0016] According to another aspect of embodiments herein, the object is achieved by a microprocessor comprising the heat spreading system.

[0017] According to another aspect of embodiments herein, the object is achieved by a closed fluid heat spreading loop adapted to be comprised in the heat spreading system.

[0018] According to another aspect of embodiments herein, the object is achieved by an electronic equipment comprising a heat spreading system.

[0019] According to another aspect of embodiments herein, the object is achieved by the heat spreading system produced by a production method comprising the following action: Creating a fluid channel of the heat spreading system in metal by using Additive Manufactured (AM) technology. The fluid channel is for the fluid to flow in the body of the closed fluid heat spreading loop between a die of the heat generating component and the heat sink.

[0020] By incorporating the closed fluid heat spreading loop comprising the fluid channel in-between the heat sink and the die, the thermal resistance between the die and the heat sink will be minimized. Which in turn results in an increased efficiency, improved reliability, and reduced energy consumption. Thus providing an improved heat spreading system for transferring thermal heat from a die of a heat generating component in an electronic equipment to a heat sink. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Examples of embodiments herein are described in more detail with reference to attached drawings in which:

[0022] Figure 1 is a schematic block diagram illustrating prior art.

[0023] Figure 2 is a schematic block diagram illustrating a cooling chain comprising embodiments herein.

[0024] Figure 3 is a schematic view illustrating examples embodiments herein.

[0025] Figure 4 is a schematic view illustrating examples embodiments herein.

[0026] Figure 5 depicts a wireless telecommunications network 100 wherein embodiments may be implemented.

[0027] Figure 6 is a diagram depicting a comparison of embodiments herein with prior art.

[0028] Figure 7 is a flowchart depicting an embodiment of a method for creating embodiments herein.

[0029] DETAILED DESCRIPTION

[0030] Embodiments herein relate to thermal heat transfer from hot components, for instance an Application Specific Integrated Circuit (ASIC), Field Programmable Gate Arrays (FPGA) or Central Processing Unit (CPU), to a heat sink, possibly incorporating Additive Manufactured (AM) metal parts. AM when used herein is also known as 3D printing, is a method of manufacturing bodies from powder, wire or sheets .

[0031] Embodiments herein may e.g. be implemented in node(s) and / or equipment(s) such as e.g. UEs, eNBs, gNBs, access points and outdoor radio equipment.

[0032] According to embodiments herein, the number of layers used in prior art is reduced by replacing the lid and the spreading device, typically a vapor chamber or a heat pipe, with a heat spreading system comprising a closed fluid heat spreading loop which may be in single fluid or two-phase fluid, wherein one-phase fluid remains in liquid form and two- phase fluid varies between liquid form and gaseous, also referred to as vapor, form.

[0033] Due to the small size of components, AM metal parts, offers possibility of individual solutions for each heated component. To make the heat transfer more effective and avoid the reliability problems over time, AM designed fluid channels in metal for liquid and / or vapor flow between a die of the heat generating component, such as e.g. ASIC, and heat sink may be designed and created.

[0034] With for example AM technology create internal fluid channels for liquid and / or vapor flow both in the ASIC capsule, also referred to as body, and heat spreader connected, which results in that no TIM layer is needed here. The internal fluid channels may e.g. be designed according to the geometry of the heat generating component, such as e.g. ASIC, and the heat spreading system.

[0035] Examples of embodiments herein provide to have one liquid and / or vapor flow directly connected from the heat generating component to the heat sink and / or heat spreading system.

[0036] By incorporating the fluid channels in the heat generating component itself, e.g., in the lid or body, the distance between the heat generating die, e.g. silicone die, to the heat sink will be minimized, thus increasing efficiency, improving reliability, and reducing energy consumption.

[0037] A number of embodiments will now be described, some of which may be seen as alternatives, while some may be used in combination.

[0038] Figure 2 depicts a cooling chain 200, wherein embodiments herein may be implemented. Figure 2 further depicts a heat spreading system 210 according to some example embodiments herein. The heat spreading system 210 is referred to as the new heat spreader in Figure 2. The heat spreading system 210 is for transferring thermal heat from a die 220 of an electronic component 225 in an electronic equipment 120 to a heat sink 230. The die 220 generates heat and may also be referred to as a silicon-based component. The die 220 according to embodiments herein, is not covered by a lid. The die 220 is e.g., placed on top of a substrate 222 that connects it to a PCB 280

[0039] The electronic equipment 120 may e.g., be a telecom equipment adapted to be comprised in a wireless communications network 100, or any electronic design based on components mounted on PCBs. The electronic equipment 120 may comprise the heat spreading system 210. The heat spreading system 210 comprises the heat sink 230, and in-between the heat sink 230 and the die 220, a closed fluid heat spreading loop 240. The closed fluid heat spreading loop 240 comprises a fluid channel 260 adapted to contain a fluid and is encapsulated in a body 270. The body 270 is in contact with the die 220 and the heat sink 230, e.g., through a TIM, to transfer thermal heat from the die 220 to the heat sink 230. The body 270 may be seen as a cover, covering the die 220 and the closed fluid heat spreading loop 240 including the fluid channel 260.

[0040] The fluid may e.g. be any one out of: a liquid, a vapor or a mixture of liquid and vapor. The body 270 may be made of any one out of: a heat conducting material, or a metal, such as e.g. AM metal.

[0041] The closed fluid heat spreading loop 240 may be adapted to be comprised in the heat spreading system 210.

[0042] The cooling chain 200 may comprise two TIM layers, TIM 1 which is used for transferring the heat from the die 220 to the new heat spreader 240, and TIM 3 which is used for transferring heat from the new heat spreader240 to the heat sink 230, plus compensate for manufacturing tolerances.

[0043] By incorporating the closed fluid heat spreading loop 240 comprising the fluid channel 260 in the heat generating component itself, such as in the new heat spreading system 210, in-between the heat sink 230 and the die 220, the thermal resistance between the die 220 of the heat generating component 222 and the heat sink 230 will be minimized, thus increasing efficiency, improving reliability, and reducing energy consumption.

[0044] Further, no TIM 2 layer is needed over lid 10 as in prior art (see Figure 1), since this layer has been removed from the electronic component 225 according to embodiments herein.

[0045] Some examples of the fluid channels 260 in the closed fluid heat spreading loop 240 are depicted in Figure 3 (a) and Figure 3 (b). Examples of the fluid channel 260 e.g. comprise microchannels with fluid 260 (a) as in Figure 3 (a) or cavity with fluid 260 (b) as in Figure 3 (b).

[0046] As mentioned above, due to the small size of the heat generating component 222, AM metal parts may be used to offer possibility of an individual design and solution for the heat generating component. To make the heat transfer more effective and avoid the reliability problems over time, the fluid channel may be AM designed and created in metal for fluid such as liquid and / or vapor flow between the die, and the heat sink 230. The die 220 as depicted in the figures is the heat generating component, e.g. a silicone die.

[0047] With for example AM technology, the internal fluid channel 260 may be created for liquid and / or vapor flow both in the body 270 of the closed fluid heat spreading loop 240, and the heat sink 230 connected, which will result in no need of any TIM layer here. The internal fluid channels may e.g. be designed according to the geometry of the heat generating component, such as e.g. ASIC, and the heat spreading system.

[0048] Some examples indicating the movement of the fluid in the fluid channels 260 of the closed fluid heat spreading loop 240 in relation to the die 220 of the heat generating component 222 are depicted in Figure 4 (a) - Figure 4 (f). The movement of the fluid is indicated by means of arrows, however, the fluid channels 260 are not shown.

[0049] In some embodiments, the fluid channel 260 inside the body 270, is configured to spread the thermal heat over the heat sink 230 in proximity to the die 220.

[0050] In some of these embodiments (a), depicted in Figure 4 (a), the fluid in the fluid channel 260 is flowing substantially parallel to the die 220. This may mean that the fluid in the fluid channel 260 is flowing alongside, beside and / or next to die 220.

[0051] In some other of these embodiments (b), depicted in Figure 4 (b), the fluid in the fluid channel 260 flowing over the_heat generating component 222 is impinging vertically towards the heat generating component 222, e.g., the die 220 of the heat generating component 222.

[0052] In some alternative embodiments, the fluid channel 260 inside the body 270 is configured to transport the heat away from the die 220 and spread it e.g., to any one out of the alternatives as described below:

[0053] In some of these alternative embodiments, depicted in Figure 4 (c), the fluid channel 260 inside the body 270 is configured to transport the heat away from the heat die 220 and spread it to a heat sink 230 plate. The fluid in the fluid channel 260 is here flowing substantially parallel to the die 120.

[0054] In some other of these alternative embodiments, depicted in Figure 4 (d), the fluid channel 260 inside the body 270 is configured to transport the heat away from the die 120 and spread it to the heat sink 230 plate. The fluid in the fluid channel 260 flowing over the die 120 is impinging vertically towards the die 120.

[0055] In some other of these alternative embodiments, depicted in Figure 4 (e), the fluid channel 260 inside the body 270 is configured to transport the heat away from the heat generating component 222 and spread it to a section of the heat sink 230 oriented in a different angle compared to the surface of the die 220 and in contact with the body 270. In the example of Figure 4 (e), it can be seen that the different angle of the orientation of the section of the heat sink 230 compared to the surface of the die 220 is 90 degrees. Here the fluid in the fluid channel 260 is flowing substantially parallel to the surface of the die 220.

[0056] In some other of these alternative embodiments, depicted in Figure 4 (f), the fluid channel 260 inside the body 270 is configured to transport the heat away from the die 120 and spread it to f a section of the heatsink 230 plate oriented in a different angle compared to the surface of the die 220. Also in the example of Figure 4 (f), it can be seen that the different angle of the orientation of the section of the heat sink 230 plate compared to the surface of the die 220 is 90 degrees. Here the fluid in the fluid channel 260 flowing over the die 120 is impinging vertically towards the die 120.

[0057] Figure 5 very schematically depicts a radio equipment 111 wherein an example of the heat spreading system 210 for transferring thermal heat from the die 220 in the electronic equipment 120 may be implemented. In this example the electronic equipment 120 is the radio equipment 111.

[0058] Figure 5 is a schematic overview depicting a wireless telecommunications network 100, such as e.g. a wireless communications network, comprising radio equipment 111 wherein embodiments herein may be implemented. The wireless telecommunications network 100 comprises one or more RANs and one or more CNs. The wireless telecommunications network 100 may use 5G NR but may further use a number of other different technologies, such as, 6G, Wi-Fi, (LTE), LTE-Advanced, Wideband Code Division Multiple Access (WCDMA), Global System for Mobile communications / enhanced Data rate for GSM Evolution (GSM / EDGE), or Ultra Mobile Broadband (UMB), just to mention a few possible implementations.

[0059] The electronic equipment 120, such as a radio equipment 111 operates in the wireless telecommunications network 100. The radio equipment 111 may e.g. be a base station, a radio unit, a base band unit, an antenna tower, an antenna pole, an antenna and / or any other radio equipment. The radio equipment 111 comprising heat generating components 222 generates heat and needs to be cooled down. It therefore comprises, e.g., is equipped with, the heat spreading system 210 according to embodiments herein. The heat spreading system 210 may e.g. be a part of the radio equipment as e.g. fins, baseplates, cooling plates, coins, metal inserts, copper inserts. The radio equipment 111 e.g. in some embodiments a base station that may be a transmission and reception point e.g. a radio access network node such as a base station, a radio base station, a NodeB, an evolved Node B (eNB, eNodeB, eNode B), an NR / g Node B (gNB), a part of an Indoor Radio Unit (IRU), an Open RAN (ORAN) node, a base transceiver station, a radio remote unit, an Access Point Base Station, a base station router, a transmission arrangement of a radio base station, a stand-alone access point, a Wireless Local Area Network (WLAN) access point, an Access Point Station (AP STA), an access controller, a UE acting as an access point or a peer in a Device to Device (D2D) communication, or any other network unit capable of communicating with a UE served by the network node 110 depending e.g. on the radio access technology and terminology used.

[0060] UEs, such as e.g. a UE 121 , operate in the wireless telecommunications network 100. The UE 121 may e.g. be an NR device, a mobile station, a wireless terminal, an loT device, an loS device, an enhanced Machine Type Communication (eMTC) device, an NR RedCap device, a CAT-M device, a Vehicle-to-everything (V2X) device, Vehicle-to- Vehicle (V2V) device, a Vehicle-to-Pedestrian (V2P) device, a Vehicle-to-lnfrastructure (V2I) device, a Vehicle-to-Network (V2N) device, a Wi-Fi device, an LTE device, a non- access point (non-AP) STA, a STA, that communicates via a base station such as e.g. the network node 110, and one or more Access Networks (AN), e.g. RAN, to one or more core networks (CN). It should be understood by the skilled in the art that the term UE relates to a non-limiting term which means any UE, terminal, wireless communication terminal, user equipment, (D2D) terminal, or node e.g. smart phone, laptop, mobile phone, sensor, relay, mobile tablets or even a small base station communicating within a cell.

[0061] According to embodiments herein, a lid and heat spreading device of prior art are replaced with the closed fluid heat spreading loop 240.

[0062] This will bring two benefits. First, as mentioned above the prior art TIM layer (TIM2) between the lid 10 shown in figure 1 and the heat generating component 50 of the PCB 60 is no longer needed. Second, the closed fluid heat spreading loop 240 has a better lower thermal resistance than the prior art lid of package, typically made of nickel-plated copper. Both of these will contribute to lowering the temperature in the die 220 according to embodiments herein. As mentioned above, the heat spreading system 210 may be designed to operate in single or two-phase regimes. The fluid may e.g. be either filled into the components after assembly or contained in the components which in this case have self-sealing connection points. The fluid channel 260 may e.g. be designed to flow parallel to the die 220 or impinging vertically on it, and the area over which the heat is released may be right beside the die 220 or away from it.

[0063] In some embodiments, a design incorporating both the body 270 such as a component capsule, and the closed fluid heat spreading loop 240 in one and the same unit may be provided. The important way to transfer heat from the die 220 to heat sink 230 is still via the fluid channel 260.

[0064] Figure 6 is a diagram depicting possible temperature improvement in the die 220 when using the heat spreading system 210. The X axis represents the power of the heat generating component and the Y axis represents the temperature gain in the die 220. The temperature gained from the closed fluid heat spreading loop 240 may vary depending on the selected flow regime, velocity, channel geometry, component power, size, etc. In Figure 6, an estimate of the possible gain area is depicted, where the minimum bound is the gain obtained by removing TIM2 layer, and the maximum by optimizing the fluid channel 260 until a high effective thermal conductivity is reached. 5000 W / mK was used for this example, other designs may reach lower or higher values. These results were obtained with simulations and analytical correlations.

[0065] In this example the heat is released beside the component.

[0066] Figure 7 shows an example embodiment of a method for producing the heat spreading system 210 by a production method.

[0067] The method for producing the heat spreading system 210 comprises the following action.

[0068] Action 701

[0069] The fluid channel 260 of the heat spreading system 210 is created in metal by using for example any of the following technologies: thin film technology, micro-nano technology, microfluidics, AM technology, and milling.

[0070] The fluid channel 260 is for the fluid to flow in the body 270 of the closed fluid heat spreading loop 240 between the die 220 and the heat sink 230. Using AM technology may e.g. mean using a type of additive manufacturing that uses a heat source, such as a laser or electron beam, to heat metal in powder or wire form so that it consolidates to form the fluid channel 260.

[0071] As mentioned above, due to the small size of the heat generating component 222, AM metal parts may be used to offer possibility of an individual design and solution for the heat generating component. To make the heat transfer more effective and avoid the reliability problems over time, the fluid channel may be AM designed and created in metal for fluid such as liquid and / or vapor flow between the die 220 of the heat generating component 222, and the heat sink 230.

[0072] The fluid channel 260 may e.g., be designed according to the geometry of the heat generating component 222, and the heat spreading system 210.

[0073] When using the word "comprise" or “comprising” it shall be interpreted as nonlimiting, i.e. meaning "consist at least of".

[0074] The embodiments herein are not limited to the preferred embodiments described above. Various alternatives, modifications and equivalents may be used.

Claims

CLAIMS1 . A heat spreading system (210) for transferring thermal heat from a die (220) of an electronic component (225) in an electronic equipment (120), to a heat sink (230), wherein the heat spreading system (210) is characterized by: the heat sink (230), and in-between the heat sink (230) and the die (220), a closed fluid heat spreading loop (240), wherein the closed fluid heat spreading loop (240) comprises a fluid channel (260) adapted to contain a fluid and is encapsulated in a body (270), which body (270) is in contact with the die (220) and the heat sink (230) to transfer thermal heat from the die (220) to the heat sink (230).

2. The heat spreading system (210) according to claim 1 , wherein the fluid channel (260) inside the body (270), is configured to spread the thermal heat over the heat sink (230) in proximity of the die (220) of the electronic component (225), and wherein any one out of:(a) the fluid in the fluid channel (260) is flowing substantially parallel to the die (220), and(b) the fluid in the fluid channel (260) flowing over the to the die (220), is impinging vertically towards the to the die (220).

3. The heat spreading system (210) according to any of the claims 1-2, wherein the fluid channel (260) inside the body (270) is configured to transport the heat away from the heat die (220) and spread it to any one out of:(c) a heat sink (230) plate, wherein the fluid in the fluid channel (260) is flowing substantially parallel to the die (220),(d) the heat sink (230) plate, wherein the fluid in the fluid channel (260) flowing over the die (220) is impinging vertically towards the heat generating component (220),(e) a section of the heat sink (230) oriented in a different angle compared to the surface of the die (220) and in contact with the body (270), wherein the fluid in the fluid channel (260) is flowing substantially parallel to the surface of the die (220), and(f) a section of the heat sink (230) oriented in a different angle compared to the surface of the die (220), wherein the fluid in the fluid channel (260) flowing over the die (220) is impinging vertically towards the die (220).

4. The heat spreading system (210) according to any of the claims 1-3, wherein the electronic equipment (120) is a telecom equipment adapted to be comprised in a wireless communications network (100).

5. The heat spreading system (210) according to any of the claims 1-4, wherein the fluid is any one out of: liquid, a vapour or a mixture of liquid and vapor.

6. The heat spreading system (210) according to any of the claims 1-5, wherein the body (270) is made of any one out of:- a heat conducting material, or- a metal.

7. An electronic component (225) comprising a heat spreading system (210) according to any of the claims 1-6.

8. A closed fluid heat spreading loop (240) adapted to be comprised in a heat spreading system (210) according to any of the claims 1-6.

9. An electronic equipment (120) comprising a heat spreading system (210) according to any of the claims 1-6.

10. A heat spreading system (210) according to any of the claims 1-6, produced by a production method comprising: creating (701) the fluid channel (260) of the heat spreading system (210) in metal by using any of the following technologies: thin film technology, micro-nano technology, microfluidics, additive manufacturing, AM technology, and milling, which fluid channel (260) is for the fluid to flow in the body (270) of the closed fluid heat spreading loop (240) between the die (220) of the electronic component (225) and the heat sink (230).

Images